High speed, direct path, stair-step, electronic connectors with improved signal integrity characteristics and methods for their manufacture

ABSTRACT

An electrical connector comprised of a plurality of electrical contacts arranged in a stair-step configuration designed to mate with electrical components having electrical contacts arranged in a stair-step configuration. A direct connect signaling system comprised of stair-step electrical connectors mated to stair-step printed circuit boards, other stair-step electrical components, or combinations thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of, and hereby incorporates byreference in its entirety and for all purposes, U.S. patent applicationSer. No. 11/868,947, filed Oct. 8, 2007 and issuing on Jan. 26, 2010 asU.S. Pat. No. 7,651,336. U.S. Pat. No. 7,651,336 is a divisional of, andincorporates by reference in its entirety, U.S. patent application Ser.No. 11/055,579, filed Feb. 9, 2005. U.S. patent application Ser. No.11/055,579 claims the benefit of and incorporates by reference U.S.Provisional Application No. 60/543,141, filed Feb. 9, 2004.

TECHNICAL FIELD

The disclosed embodiments relate generally to the field of electricalconnectors. More particularly, the disclosed embodiments relate toconnectors with stair-step structures that interface with stair-stepstructures on printed circuit boards or other electrical components.

BACKGROUND

Electronic systems that utilize printed circuit boards require some orall of the electrical signals to enter, traverse and exit the printedcircuit board. In systems that use high frequency electrical signals,the site of connections between the printed circuit board and electroniccomponents, as well as connections to other printed circuit boards, isoften the site of signal attenuation, reflection, interference and skew,all of which contribute to signal degradation that may harm theperformance of the system. System architects can maintain signalintegrity by designing connectors that lower inductance, reduceparasitic capacitance, minimize signal distortion and reflections,eliminate skew, and match impedance, wherever possible. In addition,system architects can improve signal integrity by designing connectorsthat optimize electromechanical contact force and contact wipe.

Vias, or plated through holes, in printed circuit boards can causesignificant harm to signal integrity, yet vias are commonly used to makeelectromechanical connections to printed circuit boards. FIG. 1illustrates a prior-art connector system in which the connector 101attaches to a printed circuit board 102, where the printed circuit boardcontains multiple layers 103. A conductive pin 104 is inserted into aplated through hole 105 (which consists of a hole 106, drilled throughthe printed circuit board, and an annular pad 107—both of which areplated with a conductive material). In this illustration, the platedthrough holes create anchor points for the connector, and the platedthrough hole makes an electrical connection between the conductive pin104 and a trace 108 that may be located one or more layers within theprinted circuit board.

Stair-step printed circuit board structures, examples of which appear inFIG. 1A, may limit or eliminate the need to use vias in order to makeconnections to traces that exist one or more layers below the surface ofthe printed circuit board 101 a. Traces 102 a below the surface of theprinted circuit board are exposed by the stair-step structure in whichlayers of the printed circuit board above the trace are removed. In onestair-step implementation, 103 a, the traces are exposed at edge of theprinted circuit board. In another implementation, 104 a, the traces areexposed away from the edge of the printed circuit board. Stair-stepprinted circuit board structure may require stair-step connectors bywhich electrical components can be connected to the stair-step printedcircuit board.

BRIEF DESCRIPTION OF DRAWINGS

The present invention is illustrated by way of example, not by way oflimitation, in the figures of the accompanying drawings and in whichlike reference numerals refer to similar elements and in which:

FIG. 1 illustrates fundamental prior art structures for use inconstructing electrical connectors with an enlarged view of theconnection detail.

FIG. 1A shows a stair-step printed circuit board illustrating stair-stepstructures to which some embodiments of the invention can connect.

FIG. 2 illustrates an embodiment of the invention wherein a stair-stepthe electrical contact interface has a stair-step configuration.

FIG. 3 illustrates an embodiment of a printed circuit board or otherelectrical component that allows the insulating layers, conductivetraces and ground planes on the stair-step connector to contact theinsulating layers, conductive traces and ground planes on stair-stepprinted circuit boards or other electrical components.

FIG. 4 illustrates another view of the embodiment of the invention fromFIG. 2 showing both sides of the electrical contact interfaces. Eachinterface has a stair-step structure that mates with a stair-stepstructure on the printed circuit board or other electrical component.

FIGS. 5A and 5B provide cross sectioned views of one embodiment,perpendicular to the connector's electrical signal contact interfaces.FIG. 5A shows the unmated condition and FIG. 5B shows the matedcondition as the signal conductors touch down on electrical contact padson a printed circuit board or electrical component.

FIG. 6 illustrates a cross section and an enlarged view of theembodiment of the connector in FIG. 5A in its unmated state.

FIG. 7 illustrates a cross section of an embodiment wherein theelectrical signal contact interfaces are mated with electrical contactpads of two stair-step printed circuit boards.

FIG. 8 provides a second cross sectional view of the embodiment in FIG.7, showing the ground planes or conductive return paths.

FIG. 9 illustrates a cross section perpendicular to the axis of anembodiment of the conductor beams with dielectric layers between therows of signal conductors and return paths.

FIG. 9A illustrates the traces of a stair-step printed circuit board,wherein the traces act as long electrical contact pads axially in linewith the embodiment's electrical conductors.

FIG. 10 illustrates a partially exploded view of the embodiment shown inFIG. 2.

FIG. 11 illustrates an isometric view of the top of the dielectric layer1004 contained in the embodiment shown in FIG. 10.

FIG. 12 illustrates a ground plane with rows of conductive beamsrepresentative of the ground planes contained in the embodiment shown inFIG. 10.

FIG. 13 illustrates an isometric view of the bottom of the dielectriclayer 1004 contained in the embodiment shown in FIG. 10.

FIG. 14 illustrates detail of the differential pair assembly 1005 shownin FIG. 10, including locating plates, as well as an enlarged view ofthe right end of the assembly.

FIG. 15 provides an exploded view of the differential pair assembly inFIG. 14.

FIG. 16 is the same as FIG. 15 except with the locating plates removed.

FIG. 17 is an enlarged view of the differential signal pairs in FIG. 15.

FIG. 18 is an exploded view of an embodiment of the invention in which astair-step electrical connector mates stair-step line cards with astair-step printed circuit board.

FIG. 19 illustrates the unexploded assembly in FIG. 18.

FIG. 20 illustrates FIG. 18 except with signal traces on the printedcircuit boards shown.

FIG. 21 is another embodiment of the invention illustrating a crosssection with portions of the signal conductors bent at various angles totheir mated printed circuit boards that have stair-step and planarcontact arrays.

FIG. 22 is another embodiment of the invention illustrating a crosssection with bent signal conductors mating with printed circuit boardsthat have stair-step contact pad rows.

FIG. 23 is the same as FIG. 21 except that the rightward portion of thesignal conductors is bent downward.

FIG. 24 illustrates a cross section an embodiment with conductors bentupward and downward to route the signals in different directions on thebackplane.

FIG. 25 illustrates a cross section of an embodiment of the electricalconnector showing how signals are routed from both sides of a printedcircuit board to signals traveling in different directions on abackplane.

FIG. 26 is similar to FIG. 25 except that the conductors are straight.

FIG. 27 illustrates a cross section of an embodiment of a stair-stepinterposer using, but not limited to column-buckling spring members asconductors; and interconnecting two stair-step printed circuit boards.

FIG. 28 illustrates a cross section of an embodiment of a one-sided,stair-step electrical connector that interconnects signals between twostair-step printed circuit boards.

FIG. 29 illustrates a cross section of an embodiment of a stair-stepelectrical connector interconnecting signals between two stair-stepprinted circuit boards; one printed circuit board being inverted withrespect to the other.

FIG. 30A illustrates a cross section of an embodiment of a stair-stepelectrical connector interconnecting with a stair-step printed circuitboard and with signal wires in a cable. The stair-step electricalconnector may have permanent connections between the stair-stepelectrical connector and the signal wires in the cable.

FIG. 30B illustrates a cross section of a stair-step electricalconnector interconnecting with a stair-step printed circuit board andwith conductors in a cable connector.

FIG. 31 illustrates a cross section of an embodiment of a stair-stepelectrical interposer positioned within the hole of a printed circuitboard. From this position, the interposer interconnects two or moreintegrated circuit packages or other printed circuit boards.

FIG. 32 illustrates a cross section of an embodiment of an electricalconnector with conductors whose spring force function is concentrated atthe corner of the bent conductors. The additional feature is theincorporation of the stair-step which precludes the necessity for platedthrough holes in the printed circuit boards.

FIG. 33 illustrates a cross section of an embodiment with the conductorbeams shown at, but not limited to zero and 90 degrees inclination tothe printed circuit boards. The spring members are separated from theconductors by an intervening insulated part.

FIG. 34A illustrates an embodiment of a stair-step electrical connectorwith one row of differential signal pair conductors that are rigid innature.

FIG. 34B illustrates a cross section through the electrical connector inFIG. 34A exposing the differential pair conductor assembly composed oftwo conductor beams

FIG. 35A illustrates an embodiment of a rigid conductor assembly whoseindividual conductor beams are aligned with respect to each other abouta rod serving as a pivoting axle.

FIG. 35B illustrates an embodiment of a rigid conductor assembly whoseindividual conductor beams are rotated with respect to each other abouta rod serving as a pivoting axle.

FIG. 35C illustrates an embodiment of a single conductor assemblycomposed of a pivot rod, insulating beam and conductor beam.

FIG. 36A illustrates an embodiment of an electrical connector crosssection of a leaf spring urging the rigid conductor beam into theunmated position.

FIG. 36B illustrates an embodiment of an electrical connector crosssection showing how mating forces the leaf spring to straighten out.

FIGS. 37 and 38 illustrate the slots in the dielectric layer that serveas guides for the pivot rod in the rigid conductor assembly.

FIG. 39 illustrates an isometric view of an embodiment of thedifferential signal pair assembly with leaf springs in place.

FIG. 40 illustrates an embodiment of an electrical connector crosssection of the leaf spring in an inverted position.

FIG. 41 illustrates an embodiment of an electrical connector crosssection of the differential signal pair assembly with two leaf springsdisposed in sandwich fashion on top of each other.

FIG. 42A illustrates an embodiment of an electrical connector crosssection of the rigid conductor assembly with a helical spring centeredon the conductor beam and replacing the leaf spring.

FIG. 42B illustrates an embodiment of an electrical connector crosssection of the rigid conductor assembly with helical springs disposed atthe ends of the rigid conductor beams.

FIG. 43A and FIG. 43B illustrate an embodiment of an electricalconnector cross section showing how conductive push pins, which areguided by holes in location plates, actuate spring-like, conductor beamsin unmated and mated conditions respectively.

FIG. 44A illustrates a cross section of an enlarged view of the push pinin the mated condition.

FIG. 44B illustrates an isometric view of the push pin in FIG. 44A.

FIG. 45A illustrates an embodiment of a push pin with a nail head at itstop and projecting tabs on its side.

FIG. 45B illustrates a locating plate in isometric view and a crosssection below it showing a cavity that accepts the push pin in FIG. 45A.

FIGS. 45C and 45D illustrate the push pin, the cantilever conductivebeam and the locating plate as they would operate during mating andunmating.

FIG. 46 illustrates an embodiment of the invention wherein the angledconductor beams are fixed to the electrical connector body, do not moverelative to it and have spring members at either end of the beams.

FIG. 47 illustrates an embodiment of a stair-step flexible circuit withclamping plates and a stair-step printed circuit board.

FIG. 48 illustrates an embodiment of a stair-step flexible circuitconnector with electrical connector body.

FIG. 49 illustrates an exploded view of a stair-step flexible circuitconnector above a stair-step printed circuit board with an interposerpositioned between them.

DETAILED DESCRIPTION

In the following description and in the accompanying drawings, specificterminology and drawing symbols are set forth to provide a thoroughunderstanding of the embodiments of the invention. In some instances,the terminology and symbols may imply specific details that are notrequired to practice the invention. For instance, in embodiments havinga printed circuit board, other electronic components or structures,including but not limited to flexible circuits with layers of metal anddielectric, ceramic or silicon substrates, hybrid circuits, integratedcircuits, integrated circuit packages, or a combination of them can besubstituted for the printed circuit board. Examples of printed circuitboards include, without limitation, line cards, daughter boards,daughter cards, mother boards, backplanes and so forth. Unlessspecifically stated otherwise, printed circuit boards shown or describedat a 90 or 180 degree angle to each other may be at any other angle inalternative embodiments.

Structures and methods for making direct path, three dimensionalinterconnections between stair-step printed circuit boards are disclosedherein in various embodiments. Stepped printed circuit boards describedherein refer to, for example, any of the stair-step printed circuitboard structures disclosed in U.S. patent application Ser. No.10/990,280 (“Stair-step Printed Circuit Board Structures for High SpeedSignal Transmissions”), filed Nov. 15, 2004, which is incorporatedherein by reference.

Many of the figures show two conductors that comprise a differentialsignal pair. Such conductors may use any conductive material includingbut not limited to metal-coated dielectric material, metal, conductiveelastomers or conductive plastics. The conductor traces shown may alsobe single-ended conductors, single conductors in microwave and striplinegeometries, and coaxial conductors. In figures showing a cross sectionedview, additional conductors may be present behind and/or in front of thevisible conductors. Also, while a conductor may be illustrated as havinga specific angle with respect to a printed circuit board's surface, itmay be at any angle with respect to a printed circuit board's surface.

In any figure, electrical contacts on a device's stair-step structurerepresent rows or arrays of electrical contacts on different physicallevels or layers of the printed circuit board. In other figures orwithin any one figure, electrical contacts on a given planar surface ofa device may represent rows or arrays of electrical contacts on a plane.In any figure showing a stair-step connector mating to a stair-stepcomponent, the stair-step structure on the component may be replaced bya planar connection structure. In any figure, a specific number oflayers composed of dielectric sheets, rows of conductors or groundplanes may be illustrated, but this does not limit the number of layersthat could be present in an embodiment of the invention. In electricalconnectors, electrical components, printed circuit boards, hybridcircuits, flexible circuits or the like with multiple layers ofconductive and insulating materials, all the conductive layers can beexposed for physical interconnection access by removing successivelayers in a stair-step configuration. Essentially, the first conductivelayer is exposed and made accessible by removing all the insulating andconductive layers above the first conductive layer. In sequence, thesecond conductive layer is exposed and made accessible by removing allthe insulating and conductive layers above the second conductive layer.The same procedure is followed until all desired conductive layers havebeen exposed and made accessible. An objective in removing materiallayers in this stair-step fashion is provide direct electricalinterconnection access to electrical contact pads or conductive signaltraces that are normally hidden inside the electrical device.

In embodiments of the invention, high-speed, low-complexity structuresare disclosed that facilitate fundamentally or substantially directconnection between printed circuit boards, flexible circuits with layersthat include but are not limited to metal and dielectric material,ceramic or silicon substrates, hybrid circuits, integrated circuits,integrated circuit packages, electronic components or a combination ofthem.

FIG. 1 illustrates prior art for comparison purposes.

FIG. 1 a illustrates stair-step printed circuit board structures wheretraces 102 a are exposed by the stair-step structure 103 a at the edge,or the stair-step structure 104 a located away from the of a printedcircuit board 101 a.

FIG. 2 illustrates one embodiment of the invention, which is ahigh-speed, direct-path, stair-step electrical connector 200. As shown,the connector includes the front contact interface 201. It shows anenlarged view of the stair-step configuration 202 of the rows ofelectrical contacts 203. In this embodiment of the invention, the rowsof contacts 203 shown in FIG. 2 are on different planes creating astair-step configuration 202. As a result, a stair-step electricalconnector 200 can directly contact stair-step signal traces orstair-step electrical contact pads on a target stair-step structure, forinstance on a stair-step printed circuit board.

FIG. 3 illustrates an embodiment of a multi-layer printed circuit board300, wherein signal traces or electrical contact pads 301 in one layer302 are exposed by routing or laser cutting the layer 303 above. Thisproduces a stair-step configuration 304 wherein each step has a row ofprinted circuit board signal traces and/or a continuous conductiveground plane that act as contact pad(s) with which the electricalconnector 200 can interface. The stair-step configuration 304 in FIG. 3includes two bracketing walls 305, 306 that are at right angles to thestair-step surfaces and the exposed signal traces. The walls can form aphysical boundary for the printed circuit board's stair-step that can beused to guide, mate with and protect embodiments of the invention, astair-step electrical connector 200. In another configuration, thestair-step extends to either end of the printed circuit board perimeterso that there are no walls. In another configuration the stair-stepstructure may be exposed in the center of the printed circuit board,rather than at the edge, as shown in FIGS. 1 a, 18 and 20.

FIG. 4 illustrates the front contact interface 201 and bottom contactinterface 400 with their rows of the contacts in electrical connector200 in an embodiment of the invention that connects two stair-stepstructures that would be situated perpendicular to each other whenconnected. Alignment features 401, 402 on the front and bottom surfacesalign the electrical contact pads with the corresponding electricalcontact pads on the devices that will be mated to the connector.

FIGS. 5A and 5B provide cross section views of an embodiment of theinvention showing separated and mated connections. In the cross sectionviews, perpendicular to the front and bottom contact interfaces 201, 400of electrical connector 200 in FIG. 4 showing the unmatedcantilever-beam signal conductors 500. The cantilever-beam signalconductors 500 are comprised of a central portion 502 fixed with respectto the insulating connector body 506, two cantilever beams 503 attachedto either end of the central portion 502 and two electrical contacts 504at the extreme ends of the cantilever-beam signal conductors 500. Thecantilever-beam signal conductors 500 can be single ended ordifferential signal pairs. In the unmated condition, (FIG. 5A) theprinted circuit board's electrical contact pads 501 aren't touching thecantilever-beam signal conductors 500, which are curved downward.

FIG. 5B, illustrates the mated condition of an embodiment of theinvention, in which the printed circuit board's electrical contact pads501 force the electrical contacts 504 of the cantilever-beam signalconductors 500 upward thus producing a contact force and the necessarylow contact resistance. When mated, the cantilever-beam signalconductors 500 are straight and equidistant from the cantilever-beamground conductors 800 (shown in FIG. 8) to insure a uniform,transmission line geometry throughout the electrical connector. Theelectrical contacts 504 slide along the contact pads 501 when theconnection is established, creating contact wipe and improving theconnection. The cantilever-beam signal conductors 500 combine bothelectrical and mechanical functions in one entity. The cantilever beamconductor does not incorporate any sharp twists and turns, whichenhances signal integrity for transmitted waveforms. In addition, theconductor's mechanical functions provide contact force and wipe. Boththe cantilever-beam signal conductors 500 and ground conductors 800 (notvisible in this view) are slanted at an angle to the printed circuitboards. This geometry provides the shortest physical and electricallength for the interconnect path between the contacts on the printedcircuit board and the contacts on the electrical component attached byconnector body 506.

FIG. 6 provides an enlarged view of FIG. 5 a, showing an embodiment ofthe invention in the unmated condition. The conductors 500 curvedownward from the conductor's central portion 502; and its electricalcontacts 504 protrude through openings in the electrical connector 200.A triangular space 601 around the ends of the cantilever-beam signalconductors 500 permits them to move upward as the printed circuit boardmates with the electrical connector.

FIG. 7 illustrates an embodiment of the invention in which the ends ofthe cantilever-beam signal conductors 500 are shown contacting theelectrical contact pads 501 on a backplane 700 incorporating astair-step structure and a line card 701 incorporating a stair-stepstructure

FIG. 8 illustrates an embodiment of the invention in whichcantilever-beam ground conductors 800 are shown. The cantilever-beamsignal conductors 500 (which are visible in FIG. 7) for the differentialsignal pairs are not visible in FIG. 8 because they are offset from thecantilever-beam ground conductors 800.

FIG. 9 illustrates an embodiment of the invention in which stripline isincorporated. The figure provides a cross sectional view perpendicularto the axes of the cantilever-beam signal conductors 500 in FIG. 7 andcantilever-beam ground conductors 800 in the electrical connector 200 inFIG. 2. It illustrates the physical relationships between differentsignal pairs and ground. The differential signal pair conductors 900,901 and ground planes (also called return paths) 902 comprise a coupledstripline geometry. The characteristic impedance or the differentialimpedance relies in part on the distance between the ground planes 902,on material properties, and on dimensions of other constituent parts. Anexample of changing impedance is varying the spacing between groundplanes 902.

FIG. 9A illustrates an embodiment of the invention showing a view of thestair-step printed circuit board's traces 910, which emerge from under alayer of dielectric material at left and which act as long electricalcontact pads axially in line with the conductors 911 of acantilever-beam spring connector as shown in FIGS. 6, 7 and 8. Theconductors 911 bend to produce contact force. The contact wipe movement912, produced when the connector and printed circuit board are mated, isaxially in line with the printed circuit board traces 910. This geometryallows a connector system using a smaller trace (contact pad) on theprinted circuit board than would be possible if the wipe movement werein any other direction. The axial alignment of the pads and the contactwipe movement improves the effectiveness of the connection and minimizesthe capacitive stub formed by the portion of the printed circuit boardtrace acting as a contact pad under the contact point 913.

FIG. 10 illustrates an exploded view of an embodiment in FIG. 2. Thetopmost part is the electrical connector housing 1001. The next partbelow it is the topmost ground plane 1002 with integral cantilever-beamground conductors 1003. The next part below that is the dielectric layer1004 with cavities and slots for the ground plane above it and thedifferential signal pair assembly 1005 below it. The rest of the partsare successive layers having the same functions and general shapes asthose described above. The last part lowest in the figure is thecontainment bar 1006. The containment bar 1006 and the electricalconnector housing 1001 restrains all the other parts. The differentialsignal pairs 1007 are equidistant between ground planes above and belowthem. These elements comprise differential stripline geometry.

FIG. 11 further illustrates the dielectric layer 1004 shown in 10. Arecess comprising the dielectric layer's broad cavity 1100 and its topplanar surfaces 1101 can be made into one continuous conductive surface.When the ground plane 1002 in FIG. 10 is fit into the recess in the topof the dielectric layer 1004, it will electrically isolateelectromagnetic radiation emanating from the differential signal pairsand reduce crosstalk. This configuration also reduces signal reflectionsand makes the differential impedance more uniform throughout the signalpath.

FIG. 12 further illustrates the ground plane 1002 shown in FIG. 10. Thecantilever-beam ground conductors 1200 are attached to the ground plate1201 and are tapered to reduce stress and shorten the beam length whileretaining the same contact force as would a longer, uniformly-squarecross-sectioned beam. This embodiment allows a smaller electricalconnector producing the same contact force.

FIG. 13 further illustrates the dielectric layer 1004 shown in shown inFIGS. 10 and 11. This view shows the bottom of the dielectric layer withslots 1300 and cavity 1301 for accepting the differential pair assembly1005.

FIG. 14 further illustrates the differential pair assembly 1005 shown inFIG. 10, with an enlarged view of the differential signal pairs 1400.Assembly 1005 includes two rectangular-shaped locating plates 1401 thatlocate the differential pairs dimensionally.

FIG. 15 illustrates an exploded view of the differential pair assembly1005 in FIG. 14. All of the differential signal pairs 1400 are adheredto or sputtered to the locating sheet 1600, which can be a thindielectric sheet such as polyimide. In one embodiment of the invention,a suitable etching solution, such as potassium hydroxide (KOH) canremove excess dielectric to produce the outline of the locating sheet1600. In other embodiments of the invention, a laser, machine tool orstamping tool can also cut the locating sheet's outline.

FIG. 16 illustrates the differential pair assembly 1005 without thelocating plates 1401 and the enlarged view shows two differential signalpairs 1400. In an embodiment of the invention, the differential pairsare etched from a metal foil sheet.

FIG. 17 shows the differential signal conductor beams 1701 and theirrelationships to each other in one embodiment of the invention. Thedifferential signal conductor beams 1701 are tapered to reduce stressconcentrations and shorten the conductor beam lengths while retainingthe same contact force as would a longer, uniformly-squarecross-sectioned beam. The center section 1702 of each differentialsignal conductor beam is attached to the locating plates 1401 which arein turn attached to the dielectric layers 1004.

Another aspect of the embodiment of the invention shown in FIG. 17 isthe nature of the contact area at the ends of the conductors. Theconductors may be shaped or etched into pointed or generally roundedends 1703. As shown in FIG. 9A, when a conductor 911 is placed at anangle to a contact pad 910 on the printed circuit board and the two arebrought together, the edge on the end of the conductor touches the padat a theoretical single point of contact or minimal area of contact 913in practice. This produces a large Hertzian contact stress value, whichis advantageous for creating a highly reliable, gas-tight electricalcontact. The necessary contact shape and the conductor are fabricatedsimultaneously in one operation whereas prior art often requires anadditional fabrication step to produce a pointed or spherical contactshape.

FIGS. 18 and 19 illustrate examples of stair-step line cards 1801 matedwith a stair-step backplane 1802 in exploded and unexploded viewsrespectively.

FIG. 20 shows the an embodiment of the stair-step line card of FIG. 18having signal traces 2001 on the outer surface of the backplane 2002.The signal traces may also be embedded inside the backplane's multiplelayers. As signals move through these signal traces, stair-stepelectrical connectors 2003, stair-step line cards 2004 and other signaltraces they create a daisy chain configuration.

FIG. 21 illustrates an embodiment of the invention wherein two conductorbeams 2101, 2106 are shown, each of which represents a row of conductorsdirectly behind the ones shown. The horizontally inclined portions (withrespect to the line card 2102) of the conductor beams 2101, 2106 are allof the same horizontal length in the same row. Contact points impinge onelectrical contact pads or fingers 2103 on a stair-step line card 2102.Instead of electrical contacts, the conductor beams 2101 could besoldered or welded to the line card fingers 2103. The portion of theconductor beams 2101, 2106 that are inclined at an angle to the linecard 2102 contact the electrical contact pads 2104 on the backplane2105.

FIG. 22 shows an embodiment of the invention wherein the horizontallyinclined portion of the conductors in FIG. 21 could be tilted atdifferent angles to provide different contact forces and distancesbetween rows of conductor beams 2201, 2202. The conductors could remainstraight or be in the shape of a V as shown with the vertex anywherealong the conductor beam. For instance, the angle formed with oneprinted circuit board 2103, could be 40° and the angle with the otherprinted circuit board 2104 could be 30° or there could be some othercombination of angles. This would provide a greater or lesser contactforce in the direction normal to the printed circuit board contactsurface. In another embodiment of the invention, the conductor beam2201, 2202 or portions of the conductor beam could be curved rather thanstraight. Even if the conductor cross section, length, and materialproperties are kept the same, a V-shaped conductor could provide greatercontact force while fitting into a smaller volume. This is especiallyhelpful in utilizing the stair-step electrical connector's triangularshaped volume 2105. There can be more than two rows of conductors inthis example.

FIG. 23 illustrates an embodiment of the invention similar to theelectrical connector in FIG. 21 except that the inclined portion 2301,2302 of the conductor beams are bent downward toward the backplane 2303,which significantly reduces the height (H) of the electrical connector.

FIG. 24 shows an embodiment of the invention wherein the inclinedportion of the conductor beams 2401, 2402, 2403 and 2404 are bent bothupward and downward. This configuration allows the signals to routedirectly from one side of the line card 2405 to signal traces thattravel in opposite directions on the backplane 2406.

FIG. 25 illustrates an embodiment of the invention wherein thestair-step electrical connector 2501 interfaces with both sides of theline card 2502 and routes the signals to stair-step contact pads 2503and sends the signals in either direction on the stair-step backplane2504.

FIG. 26 illustrates an embodiment of the invention wherein the printedcircuit board configurations are the same as in the previous embodimentof the invention in FIG. 25 except the conductor beams 2601 are straightrather than bent.

FIG. 27 illustrates an embodiment of the invention wherein a stair-stepinterposer 2700 connects directly to the signal traces 2701 of twoparallel stair-step printed circuit boards 2702, 2703 thus avoiding theneed for plated through holes. The conductors 2704 shown are similar tothe V-shaped conductor spring beams 2201 shown in FIG. 22 except thatthe printed circuit boards 2702, 2703 are parallel to each other. Theconductors 2704 can be any type of spring-like member that interconnectsto the electrical contact pads on the stair-step surfaces of the printedcircuit boards 2701, 2703.

FIG. 28 illustrates an embodiment of the invention wherein a stair-stepelectrical connector 2801 interconnects to the electrical contact padsof two stair-step printed circuit boards 2802, 2803. The conductors areslanted, cantilever beam conductors 2804 with spring-like properties.

FIG. 29 illustrates an embodiment of the invention wherein a stair-stepelectrical connector 2901 is similar to the one in FIG. 28 except theprinted circuit boards 2902, 2903 are inverted with respect to theother.

FIG. 30A illustrates an embodiment of the invention wherein a stair-stepelectrical connector 3001 interconnects a stair-step printed circuitboard 3002 directly to the ends of wires 3003 in a cable 3004.

FIG. 30B illustrates another embodiment of the invention wherein astair-step electrical connector 3011 interconnects a stair-step printedcircuit board 3012 directly to an electrical connector 3013 attached toa cable 3014. The conductors in the electrical connector 3001 or 3011may be articulated in another direction, relative to the printed circuitboards, than is shown in FIG. 30A or 30B so that the axis of the cable3004 or electrical connector 3013 can be at any other angle to thestair-step electrical connectors or the printed circuit board.

FIG. 31 illustrates another embodiment of the invention, a stair-stepelectrical interposer 3100 which resides in a hole in a printed circuitboard 3101 so that stair-step electrical interposer's contacts 3102 areexposed on either side of the printed circuit board 3101. Other printedcircuit boards or IC packages 3103, 3104, 3105, 3106 having stair-stepelectrical contacts 3107 can interface with the stair-step electricalinterposer 3100. This configuration allows signals to travel to theother side of printed circuit board 3101 with improved signal integrity.The conductors 3108 are similar to the V-shaped conductor spring beams2201 shown in FIG. 22 except that the printed circuit boards 3103, 3104are parallel to printed circuit boards 3105, 3106. The conductors 3108can be any type of spring-like conductive member that interconnects tothe electrical contact pads on the stair-step surfaces of the printedcircuit boards 3103, 3104, 3105, and 3106.

FIG. 32 illustrates an embodiment of the invention, an electricalconnector 3200 whose electrical conductors 3201 are fabricated from onepiece of metal or conductive material. Each conductor is a spring thatcreates contact force on the ends 3202 of the conductor, when either legof a conductor is displaced by mating it with electrical contact pads3203 on the printed circuit boards 3204, 3205. The electrical connectorhas a stair-step configuration 3206 of electrical contacts that allow itto electrically interface with the stair-step arrangement 3206 on theprinted circuit board 3205. The printed circuit board 3204 and theinterconnection interface on the right side of electrical connector 3200illustrate how the two components may mate without a stair-steparrangement.

FIG. 33 shows an embodiment of the invention of an electrical connector3300 that eliminates the need for plated through holes (vias) by addinga stair-step feature 3301 to the line card 3302. The conductors 3303,3304 are straight (rather than v-shaped) and inclined at a zero angle tothe line card 3302. The conductors make contact with the electricalcontact pads 3305 on the backplane 3306. The other end of the conductors3303, 3304 simultaneously wipes and makes contact with the signal traceon the line card 3302. Springs 3307 are separated from the conductors3303, 3304 by insulating members 3308. The springs 3307 push against theinsulating members 3308, which push against the conductors 3303, 3304 toprovide contact force against the backplane's electrical contact pads3305. The electrical contact pads 3305 are shown in a planarconfiguration, but could also be on different layers in a stair-stepfashion as shown in FIG. 3. The spring 3307 could be any type ofmechanism such as a helical spring, torsion spring, cantilever beamspring, elastomer or a bladder filled with a liquid or gas. Rather thanhaving a separate spring member for each conductor, the springs could befabricated as one entity wherein portions of the spring member could bearticulated to move separately and provide force for each conductor in arow or for conductors in any segregated group. Thus the spring member isless costly to manufacture, assemble and handle since one item isfabricated for a group of conductors rather than separate springs foreach conductor. Since the springs are separated from the conductors,mechanical requirements do not force the conductors to have awkwardshapes that are detrimental to uniform impedance requirements.

FIG. 34A illustrates an embodiment of the invention in which theelectrical connector 3400 interconnects printed circuit boards (notshown) oriented at an angle to each other and whose conductor beams3401, 3402 are rigid or stiff in nature. A separate spring (not shown)provides the contact force for each conductor beam 3401 or 3402.

FIG. 34B illustrates a cross section through the electrical connector3400 exposing the differential pair conductor assembly 3410 composed oftwo conductor beams 3401 and 3402. The conductor assembly may also becomposed of one conductor or more than two conductors.

FIGS. 35A, 35B illustrate a differential pair conductor assembly 3410comprised of five parts. There are two insulating beams 3501 made ofceramic or other suitably stiff or high elastic modulus insulatingmaterial. Two conducting beams 3401, 3402 are adhered in some fashion tothe bottoms of the insulating beams 3501. Or the conducting beams aremade by conductively coating, sputtering or plating the bottoms of theinsulating beams 3501. Next, a pivot rod 3503 is inserted into the holein the center of the insulating beams 3501. Each conductor beam 3401,3402 in the differential pair assembly 3410 can rotate about the pivotrod 3503. This allows conductor beam 3401 to rotate separately from theother conductor beam 3402 as shown in FIG. 35B. This action insures thatwhen each conductor contact 3504 (at either end of the conductor beams3401, 3402) touches and mates with a mating contact pad, it doesn'thinder the movement or decrease the contact force of the conductorcontact 3504 next to it.

FIG. 35C illustrates a single conductor assembly 3520 composed of pivotrod 3521, insulating beam 3522 and conductor beam 3523.

FIG. 36A shows the same cross section view of electrical connector 3400in FIG. 34B. The curved leaf springs 3601 provides force to the top ofthe differential pair assembly 3410 or to the top of the singleconductor assembly 3520 in FIG. 35C. The electrical connector 3400 isshown just as the electrical contacts on the ends of the conductor beam3402 begins to touch the mating electrical contact pads 3603 on theprinted circuit boards 3602.

FIG. 36B shows the electrical connector 3400 fully actuated and mated.The printed circuit boards' mating electrical contact pads 3603 havepushed the conductor assemblies, either 3410 or 3520 so that the leafspring 3601 is flattened out or nearly flattened out and has createdadequate contact force at either end of the conductor beam 3402.

FIGS. 37 and 38 illustrate the interaction between the differential pairassembly 3410 and a slot 3701 in the surrounding dielectric 3702. InFIG. 38, the dielectric 3702 is shown in cross section 3800 so that thedielectric's right half is not shown. Either end of the pivot rod 3503slides inside the slots 3701 in the surrounding dielectric 3702. Oneslot 3701 is shown partially in FIG. 37 and fully in view in FIG. 38 andthe other slot is in the dielectric (not shown) on the opposite side ofthe differential pair assembly 3410 and captures the other end of thepivot rod 3503. The two actions: 1.) the conductor beams 3401, 3402rotating about the pivot rod 3503 and 2.) pivot rod 3503 sliding in thedielectric's slots 3701 allow the contacts 3504 at each end of theconductor beams 3401, 3402 to electrically interface with electricalcontact pads 3603 on printed circuit boards 3602. The leaf springs 3601can be any type of spring including 2 or more leaf springs, helicalsprings, torsion springs, elastomers or other force mechanisms such asbladders filled with a compressible material such as air. The separationof the force-producing spring 3601 from the conductor beams 3401, 3402allows the designer to separate the electrical design constraints of theconductor beams from the mechanical design constraints of the spring,thus the spring 3601 can be nonconductive. The conductor beams 3401,3402 in the conductor assembly have a uniform cross section throughouttheir length thus insuring uniform differential impedance. In theprevious design, a conductor combined both electrical and mechanicalpurposes. They were tapered to lower the stress, but the taper doesn'tproduce as uniform a cross sectional shape or as uniform a differentialimpedance throughout the length of the differential signal pair asconductor beams 3401, 3402.

FIG. 39 illustrates, in isometric view, the differential pair assembly3410 with conductor beams 3401, 3402 one behind the other. The leafsprings 3601 are in their unstressed, rest positions with their concavesides 3900 pointed upward.

In FIG. 40, the leaf springs 4001 are reversed, so the spring's midpoint4002 touches the uppermost restraining layer 4003. Both ends of the leafspring project downward toward the ends of the insulating beams 3501.

FIG. 41 illustrates an embodiment of the invention wherein two or moreleaf springs 4101 are placed one atop the other. The leaf springs 4101are thinner than those previously discussed to reduce stress levels inthe outside fibers of the metal. The force upon the insulating beam 3501is multiplied by the number of leaf springs 4101 placed together on topof each other. As an example, two leaf springs 4101, one atop the other,have twice the force of one leaf spring 4101 for the same deflectionwhile stress in the outside surface of one leaf spring 4101 is less thanthe stress in one leaf spring with twice the thickness T.

In FIG. 42A, a helical spring 4201 replaces the leaf spring 3601, 4001or 4101 at the center of the insulating beam 3501. In FIG. 42B, twohelical springs 4202 are located at the ends of the conductor beam. Thehelical springs can be replaced with any other spring-like member suchas a column-buckling spring, a torsion spring, a conductive elastomericbutton or other force mechanisms such as bladders filled with materialssuch as gases or liquids.

FIG. 43A illustrates an embodiment of the invention wherein two pushpins 4301 are located at the ends of the slanted conductor beam 4302.The push pins 4301 are captured within guiding holes of two locationplates 4303 that are angularly disposed to each other. In FIG. 43B, whenthe electrical connector 4300 is mated with electrical contact pads 4305on printed circuit boards 4304, the push pins 4301 move toward theconductor beam 4302. The conductor beam 4302 is held or fixed at itscenter and is free to bend at either end. As the push pins 4301 move,they bend the cantilevered ends of the conductor beam 4302 upward, whichin turn provide force for low contact resistance between the ends of theconductor beam 4302 and the electrical contact pads 4305. As the pushpins move, the contact ends of the conductor beams 4302 slide across themating surface of the tops of the push pins 4301 thus providing contactwipe.

FIGS. 44A, 44B illustrates an added property wherein an insulatingcollar 4401 is placed around the push pins 4402. This collar acts as astop that prevents the push pins from being pushed out of the locationplates 4303. The insulating collar 4401 is made of a material with thecorrect dielectric constant to match that of the location plate. Thusthe push pin 4402, which is conductive, will have a bettermatched-impedance than those of a push pin made with an integralconductive collar. An integral conductive collar would bounce backsignal waveforms causing disruptive reflections and degrade signalintegrity. The push pins 4402 could be made very small, which isadvantageous for making a uniform transmission line that producesuniform characteristic impedance. Manufacturing technology allows theguiding holes 4403 in the locating plates 4303 to be very accuratelyfabricated with regard to size and their location with respect to eachother. The locational accuracy of the electrical contacts in electricalconnector 4300 is much greater than any of the other arrangementspreviously shown in this and other disclosure documents that describeelectrical connectors.

FIGS. 45A and 45B illustrate an embodiment of the invention wherein thepush pin 4501 slides and revolves inside a guiding hole 4505 in thelocating plate 4506. Locating plate 4506 has the same function aslocating plate 4303 in electrical connector 4300. Projecting tabs 4502would fit into slots 4504 in guiding hole 4505. The slots 4504 (thereare two in guiding hole 4505) would be twisted with respect to thehole's axis. In FIGS. 45C and 45D, the printed circuit board contact pad4507 mates with the push pin 4501 causing it to move upward inside theguiding hole 4505 in the locating plate 4506. Simultaneously, theprojecting tabs 4502 would revolve with respect to the push pin's axisbecause of the slot's twisted geometry. This action makes the push pin4501 twist, producing contact wipe in two places as shown by the arrows:1.) between the push pin and the printed circuit board's contact pad4507, 2.) between the cantilever beam 4508 and the top of the nail head4503 on the push pin 4501.

FIG. 46 illustrates an embodiment of the invention wherein the angledconductor beams 4601 can be fixed to the electrical connector body 4602and do not move relative to it. Two locating plates 4603, which are atan angle to each other, are fixed to the electrical connector body 4602.Spring members 4604 are placed in locating holes in the locating plates4603 and make electrical contact with the ends of the angled conductorbeams. When the electrical connector 4600 is mated to the electricalcontact pads 4605 of printed circuit board 4607, it deflects the springmembers 4604 to electrically connect the electrical contact pads, springmembers and angled conductor beams. Printed circuit board 4606illustrates the unmated condition before the spring member deflects.Alternatively, the spring members 4604 may be placed in or on theprinted circuit boards and the angled conductor beams 4601 configured invarious ways to allow electrical contact with the spring members.Alternatively, the spring members 4604 could be any force-producingmechanism such as a fuzz button, a helical spring, a column-bucklingspring, a bellows spring, a conductive elastomeric button, a zebraelastomeric strip, a pogo pins, a bladder with a material within that iscapable of being compressed, a PariPoser contactor from PariconTechnologies Corp or the like. Placing spring members inside holes inthe locating plate 4603 increases the locational accuracy of theelectrical connector's contacts with respect to each other.

FIG. 47 illustrates another embodiment of the invention that usesmultiple, stacked layers of metal foils and dielectric sheets in aflexible circuit 4701. At either end of the flexible circuit, each metallayer is exposed by extending it beyond the adjacent layer. This createsa stair-step configuration 4702 at either end of the flexible circuitwhose rows of electrical contacts 4703 interface with rows of electricalcontact pads 4705 on stair-step printed circuit boards 4706. Eitherfigure shows the rows of contacts 4703 at either end of the flexiblecircuit 4701 being 90 degrees to each other, but they may be at anyother angle or even in the same plane. Thus printed circuit boards 4706may be at angles other than 90 degrees. The flexible circuit 4701 can belengthened, branched and articulated into many different configurations.Separate clamping plates 4704 clamp the ends of the flexible circuit4703 to printed circuit boards, circuits in general, other flexiblecircuits, cables, other electronic components or electrical connectors.

FIG. 48 illustrates another embodiment of the invention, a stair-stepflexible circuit connector 4801 wherein the stair-step flexible circuit4701 is integral with an electrical connector body 4802. As in theembodiment of the invention shown in FIG. 47, the rows of contacts ateither end of the flexible circuit 4801 are 90 degrees to each other,but they may be at any other angle or even in the same plane. Thusprinted circuit boards may be at angles other than 90 degrees. Thecurved portion 4803 of the flexible circuit 4701 between the rows ofcontacts is shown as rounded. However, it may be flat so that thesignals may travel the smallest possible distance between contacts thatare at the ends of the flexible circuit.

FIG. 49 illustrates an exploded assembly showing the stair-step flexiblecircuit connector 4801 and a stair-step printed circuit board 4706. Aninterposer 4901 is inserted between the stair-step flexible circuitconnector 4801 and the stair-step printed circuit board 4706. Theinterposer 4901 shown has a stair-step configuration and could becomposed of a z-axis conductive film, a z-axis conductive adhesive film,a PariPoser contactor from Paricon Technologies Corporation or arrays ofany type of individual conductive members. The interposer 4901 couldalso be a dielectric film that prevents current flow between theelectrical connector and the printed circuit board, but does allowsignals to be received through capacitive coupling.

Relative to FIG. 47 through FIG. 49, another embodiment of the inventionis to etch the electrical connector contacts from the metal foil in theflexible circuit into any spring-like member such as a cantilever beamor leaf spring or the like. Each of these spring members can bemechanically shaped or curved so that mating the electrical connector tothe printed circuit board's electrical contact pads will provide contactforce. Another embodiment of the invention is to shape the ends of theflexible circuit's signal traces, which are electrical contacts, intoseparate projections that have the appearance of teeth in a comb. Thispermits each of the contacts to move independently of the other signaltraces. The contact in this embodiment can provide contact force orthere can be an additional spring member inducing force upon eachcontact to provide contact force during mating. The movement of anycontact does not hinder the contact force associated with adjacentcontacts and, thus, a separate part such as an interposer is notnecessarily required.

Although the invention has been described with reference to specificexemplary embodiments of the invention thereof, it will be evident thatvarious modifications and changes may be made thereto without departingfrom the broader spirit and scope of the invention. The specificationand drawings are, accordingly, to be regarded in an illustrative ratherthan a restrictive sense.

1. An electrical connector comprising: one or more dielectric andconductive elements having a plurality of electrical contacts arrangedin first and second stair-step configurations on different sides of theelectrical connector; and wherein in the stair-step configurations, theplurality of electrical contacts are disposed to mate with correspondingelectrical contacts of one or more electrical components, whereinrespective ones of the plurality of electrical contacts on the differentsides of the electrical connector are electrically connected to oneanother via a cantilevered-beam signal conductor passing through a bodyof the electrical connector.
 2. An electrical connector assemblycomprising: a first insulating member having first and second surfaces;a first plurality of cantilever beam conductors secured adjacent thefirst surface of the first insulating member; and a second plurality ofcantilever beam conductors secured adjacent the second surface of thefirst insulating member, wherein a cantilever beam conductor has a firstend, a second end, and a mid-section between the first and second ends,wherein the first surface of the first insulating member has a firstplurality of slots; and, each of the first plurality of cantilever beamconductors are disposed, at least in part, within a corresponding slotfrom among the first plurality of slots.
 3. The electrical connectorassembly of claim 2 wherein: the second surface of the first insulatingmember has a second plurality of slots; and, each of the secondplurality of cantilever beam conductors are disposed, at least in part,within a corresponding slot from among the second plurality of slots. 4.The electrical connector assembly of claim 3 wherein the secondplurality of cantilever beam conductors are in electrical continuitywith each other.
 5. The electrical connector assembly of claim 4 whereinthe mid section of the second plurality of cantilever beam conductorsare coupled with a conductive ground plate.
 6. The electrical connectorassembly of claim 5 wherein the second plurality of cantilever beamconductors and the ground plate are integrally formed from a singleconductive member.
 7. The electrical connector assembly of claim 6wherein the second plurality of cantilever beam conductors are taperedsuch that a cross section of a cantilever beam conductor is widerproximate the ground plate and narrower proximate its respective firstand second ends, thereby maintaining a cross sectional beam area moreclosely proportional to a sheer force exerted at any point along acantilever beam.
 8. The electrical connector assembly of claim 4 whereina border of the first insulating member extends proximate the first andsecond ends of the second plurality of cantilever beam conductors. 9.The electrical connector assembly of claim 4 wherein the firstinsulating member comprises a conductive layer electrically isolatedfrom the first plurality of cantilever beam conductors and in electricalcontinuity with the second plurality of cantilever beam conductors. 10.The electrical connector assembly of claim 9 wherein the first pluralityof cantilever beam conductors are arranged in a linear arrangement, andwherein the first ends of the respective first and second plurality ofcantilever beam conductors comprise conductive components ofcorresponding first and second steps of a first stair step electricalinterconnect structure on a side of the electrical connector assembly.11. The electrical connector assembly of claim 10 wherein the firstplurality of cantilever beam conductors are segregated into a firstplurality of differential pairs, each differential pair having first andsecond cantilever beam conductors.
 12. The electrical connector assemblyof claim 11 wherein a space between adjacent cantilever beams of adifferential pair of cantilever beams is less than a space betweenadjacent cantilever beams of separate differential pairs.
 13. Theelectrical connector assembly of claim 11 further comprising a thirdplurality of cantilever beam conductors, the first ends of the thirdplurality of cantilever beam conductors arranged in a linear arrangementcomprising conductive components of a third stair step of the firststair step electrical interconnect structure.
 14. The electricalconnector assembly of claim 13 further comprising: a second insulatingmember having first and second surfaces; a third plurality of slotsformed in the first surface of the second insulating member, wherein thethird plurality of cantilever beam conductors are disposed, at least inpart, in corresponding slots from among the third plurality of slots.15. The electrical connector assembly of claim 14 wherein the secondinsulating member further comprises a conductive ground layer inelectrical continuity with the second plurality of cantilever beamconductors.
 16. The electrical connector assembly of claim 14 whereinthe third plurality of cantilever beam conductors are in electricalcontinuity with each other, and with the conductive ground layer of thesecond insulating member.
 17. The electrical connector assembly of claim16, wherein: the second surface of the second insulating membercomprises a fourth plurality of slots; the second surface of the secondinsulating member faces the first surface of the first insulatingmember; and first plurality of cantilever beam conductors are disposed,at least in part, in corresponding slots of the fourth plurality ofslots.
 18. The electrical connector assembly of claim 14 wherein thesecond surface of the second insulating member faces the second surfaceof the first insulating member,